1. Field of the Invention
The present invention relates generally to a seal polishing device. More specifically, this invention relates to a polishing arrangement for the flanges on the heads and vessels of a nuclear reactor. Still more particularly, this invention relates to an apparatus for polishing an annular flange using a relative motion detection.
2. Description of the Related Art
An interface defined between a nuclear reactor vessel and a head which closes the vessel is sealed by metallic O-rings which are disposed between the vessel flange and the vessel head flange. The vessel head flange is usually provided with grooves for receiving the O-rings. On the other hand, the flange on the vessel is usually flat. Thus, O-Rings are installed each time the reactor vessel is opened for refueling.
While the vessel is open, the sealing surfaces are carefully cleaned to remove oxide particles remaining from the former O-rings before the new O-rings are installed and the reactor vessel is closed again. Failure to adequately clean the flange/groove surfaces may lead to leakage and a need to remove the vessel head again.
Closure and hydro tests of the reactor pressure vessel are normally performed during outage critical time following the closure of the vessel. These tests require time and effort and accordingly, undesirable costs are incurred in addition to prolonged down time, in the event that the reactor vessel has to be opened again because of leakage.
The cleaning of the surfaces is usually carried out by hand. The surfaces are difficult to reach and the environment in which they are located demands that the operators use respirators and protective garb. Accordingly, as the operator's visibility is inevitably reduced by the protective suiting/respirator apparatus, it very difficult for the operator to observe accurately the surfaces which are being cleaned. These handicaps often result in the surfaces being cleaned to a bare minimum and invite the above mentioned leakage problems.